1. Field of the Invention
The present invention relates to a half precast slab (e.g. a half precast floor slab) and a method for structuring the half precast slab that is mainly applied to a thick slab needed for a turbine foundation in a power generation house or other structures. Further, the present invention relates to a method for structuring a slab by use of the half precast slab.
2. Background of the Invention
In a construction work applying reinforced concrete (i.e. ferroconcrete), a precast construction technique is finding increasing use instead of cast in-situ concrete approach; thereby, in the precast construction technique, a plurality of reinforced concrete members manufactured in a factory are conveyed to a construction site where each reinforced concrete member is placed at each predetermined location and each adjacent reinforced concrete members is joined to the adjacent member. Thus, the reinforced concrete structure by use of the precast construction technique is formed in site.
According to the precast construction technique, a series of construction work processes in site such as structuring concrete-forms, curing the concrete installed in the concrete-forms and removing the concrete-forms can be omitted; further, the reinforcing bar arrangements in laying the reinforcing members in an area where concrete is installed can be omitted in a case where reinforcing bars are previously embedded in the precast construction structure; hence, the construction time in relation to the whole reinforced concrete work can be cut to a large degree.
The precast construction technique is classified into two major categories: the full precast construction technique, and the half precast construction technique; in the full precast construction technique, the whole precast member is manufactured as a precast structure; in the half precast construction technique, a part of a precast member is manufactured at a factory or at the site as a precast structure, and the remaining part of the member is manufactured at site by installing concrete into the precast structure brought in the site. When there is an apprehension of the weight increase regarding the member manufactured by the full cast construction technique as well as the expenditure increase due to the weight increase, then the half precast construction technique is preferably chosen.
In general, in applying the half precast construction technique to a floor structure, the part that corresponds to the floor concrete form in a case of the cast in-situ concrete is previously manufactured as a half precast floor structure (i.e. a half precast slab) at a factory; the manufactured half precast slab is conveyed to the site and each end side of the half precast slab is placed on a beam (namely, on the predetermined position); after the arrangement of the reinforcing bars as needed is performed in the space over the half precast slab, concrete is installed into the space over the precast slab; thus, an integrated composite slab (structure) is formed.
According to the half precast construction technique as described above, the wood form needed in structuring the slab in the site can be dispensed with; the advantage inherent in the precast construction technique can be made use of; further, thanks to the weight reduction due to the choice of the half precast structure, the easiness regarding the component conveyance and installation can be achieved.